Lamps are classified according to light-emitting angle of LEDs arranged on a LED board, and the LED board of a commonly-used lamp is usually horizontally placed, in this way, the light-emitting angle is between 120 degrees and 180 degrees. If a light-emitting angle above 275 degrees is desired, an optical lens or reflector panel has to be applied to the LED board, alternatively, the LED board has to be vertically placed to make the light reflected downward, however, the space above the lamp may thus be dark. Therefore, additional LED boards are needed to be installed on the vertically-placed LED board so as to solve the problems of lighting difficulty above the lamp.